Using Mentor Graphics

Design Kit

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Table of Contents

Table of Contents ……………………………………………………………. 2 Using the Design Kit …..…………………………………………………….. 3 Software Requirements ……………….……………………….…………… 3 Prerequisites ………………………………………………………...………… 4 Design Kit contents …...……………………………………………….. 4 Creating a Project …………………………………………………………….. 5 Creating a Library …………………………………………………………….. 10 Creating a Schematic Cell View…………………………………………….... 11 Simulating Schematic……………………………………………………….... 24 Creating a Layout Cell View…………………………………………………. 30 Verification of Layout…………………………………………………………. 36

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Using the Design Kit The Design Kit is designed to provide an introduction to the analog design flow using the Mentor Graphics Custom IC Design products, which include ICStudio, Design Architect-IC and the ICgraph Suite of tools. It includes all the necessary items to guide you through the process of creating a schematic, setting up a testbench, simulating a design and laying out that design.

With the lessons that follow you will also become familiar with the analog design flow into the EldoTM simulation product using the ICNet netlister. The Eldo simulator offers numerous simulation and modeling options for SPICE- level simulations. Its unique "divide and conquer" partitioning scheme allows use of different algorithms on differing portions of a design, yielding high-accuracy in combination with high performance.

ICStudio manages the flow. It calls the Front End and Back End tools. The tools load the userware of this kit. The userware is designed in a way that enables you to use the tools efficiently. The dialog boxes give you the option to enter the device properties in different combinations. For example, you can enter two parameters of (R, W and L) of a resistor, and the dialog box will calculate for you the third value. In addition you can check the entered and calculated values for each device to avoid out of range values.

Software Requirements 1. Design Architect – IC v2005.1_1.1 or greater. (To check the version, enter the da_ic -ver command.)

2. Eldo version 6.5_1.1 or greater. (To check the version, enter the $anacad/bin/eldo -rel command.)

3. ICgraph v2005.1_1.1or greater. (To check the version, enter the ic -ver command.)

4. Calibre.

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Prerequisites 1. You must have MGC_HOME pointing to a valid installed Mentor Graphics Flow 2005.1 tree or a more recent release

2. You must have the Anacad software installed on your network and accessible via $anacad.

3. In order to enable SPE in classic flow, do the following:

- Type da_ic in a terminal

- Select Setup > Session

- Select Property Editing

- Mark Enable Structured Property Editing (SPE)

- Click OK

- Select Setup > Save Setup , then close the da_ic

Design Kit Contents

Go into the installed design kit directory then list it by typing ls.

The following sub-directories will be listed.

pdf_docs - This directory is where the User Guide of the Kit exist.

models - This directory is where the models exist.

symbols - This directory contains all the kit symbols.

userware - This directory contains the DA-IC and IC Station userware.

process - This directory contains the design kit’s process definition files.

rule_deck - This directory contains foundry Calibre rule files.

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Creating a Project Step 1 To invoke ICStudio do the following:

Open ICStudio by typing the command icstudio &

The ICStudio interface will be invoked and appear on the screen

Menu Bar and Icons Area

Libraries Area

Cells Area

Views Area

Transcript Log Area

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Step 2 To create a project click on File > New > Project from the menu bar. The New Project setup wizard will open to help you in creating the new project. Press Next to proceed with the wizard.

Step 3 Enter the project name and browse for the project location and then press Next.

Step 4 Press on the Open Library List Editor button to set your location map.

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Step 5 Select Edit Menu followed by Add MGC Design Kit. This will add a row with a library name MGC_DESIGN_KIT. Browse for the kit installation directory in the location area.

Step 6 To add the standard libraries, select Edit Menu, and then select Add Standard MGC Libraries.

Step 7 After that press OK. This will return you back to the main wizard. Press Next to proceed.

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Step 8 This will move you on to the Technology Settings. Press Open Setting Editor to set the technology settings.

Step 9 Browse for the paths of the Process file, DRC, LVS, SDL and PEX rules files.

Step 10 Click on Miscellaneous tab. Write “$MGC_DESIGN_KIT/userware” in the AMPLE_PATH field.

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Step 11 Press OK to return back to the main wizard. A summary of all the previous steps will then be shown.

Step 12 Press Finish to finalize F. This is how the ICStudio interface will look like after creating the new project.

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Creating a Library Step 1 To create a library click on File > New > Library from the menu bar. A window

will pop-up asking you for the library name.

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Creating a Schematic Cell View Step 1 To create a schematic cell click on File > New > View from the menu bar. A

window will pop-up asking for the cell name, and view type. Let the cell name be inverter and choose Schematic as view type, the view name will be named automatically Schematic.

Step 2 By Pressing Finish this will open the Design-Architect IC for you.

Workspace

Left Icon Palette

Icon & Menu bar

Pull Down Menu

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The graphic interface is divided into four main sections – a menu bar, a workspace, and a palette.

The menu bar and palette change to reflect the design task you select – laying out a schematic, setting up a testbench, or simulating a design. [As you are working with your design you will notice that the gray bar below the menu (the Info bar) contains information that changes dynamically as you go about your tasks.] The workspace provides a snap to grid for manipulating primitive-level components or higher level symbols.

Function key shortcuts Function key shortcuts provide quick one- or two-button access to common tasks like Copy, Paste, Select All, Unselect All. The function keys work in conjunction with the Shift, Control and Alt keys to provide up to four separate actions per key. To display function key shortcuts select Setup > Session and select Show Softkey Area.

Strokes with middle mouse button Design Architect–IC provides a number of shortcuts to common actions by utilizing the middle mouse button. While holding down the middle mouse button you can make simple, alphabet-like strokes in the workspace to quickly copy, move, zoom in or out, view an area or view all, delete or undo, unselect all and flip horizontally... to name just a few. To display the Quick Help on Strokes dialog box draw “?” with the middle mouse button.

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Hot keys Hot keys also provide shortcuts to a lot of functions. To get the complete list of hot key select Setup> Hotkeys > Report.

Creating a Schematic In this section you will become familiar with placing primitive analog devices for a inverter. You’ll learn how to:

• place primitives on the schematic

• select and manipulate devices

• customizing hotkeys for placing devices

• route devices

• edit device parameter values

• name instances

• check and save the schematic

• create upper hierarchical symbols

• create test bench

• simulate using Eldo

• view results

Primitive devices are selected from the design kit device library shipped with Design Architect-IC.

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Creating an Inverter Placing Devices Step 1 From the left icon palette press on Add Device icon . The Device List dialog box

containing the entire device list for this process will pop-up. You can also press key a to call the same dialog box.

Step 2 Select the nfet , press OK. The Add Instance window is open, You can enter the required values for W,L,NF and Mt, press OK, Place the nmos transistor in the schematic.

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Step 3 Press on Add Device again, select the pfet ,then press OK and place the pmos.

The schematic should now look as follows

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Adding Ports and Connecting the Devices Step 1 Power could be added by pressing “Add Instance” icon in the left icon palette or

the hot key i. This will call the Add Instance window. Browse and Select the MGC_IC_GENERIC_LIB library followed by ground cell and its Symbol view. Place it in the schematic window. Do the same for Vdd.

Step 2 Place the IN and OUT ports in a similar way or by pressing the “Add Port” icon in the left icon palette.

Step 3 Place the cursor over the NET on the port. Click “q”. This will bring up a form as shown below. Select the NET line in the box, Enter IN for the net name in the Value.

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Step 4 Do the same for the OUT port ,Enter OUT in the NET name

Step 5 Connect the devices by dragging the mouse from the pin of the device. You can also use the hot key w.

Step 5 Do the same for the OUT net. The schematic should now look as follows.

Step 6 Click Check and Save from the above palette.

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Changing Parameter Values Your schematic is complete and you will now need to create a testbench for simulation. You can manipulate devices and change device parameters by the following method that is described below. If you are satisfied with the devices you may skip to the section entitled generating a Symbol to continue.

Edit Object Properties

To change parameters on a device , You may use one of the following 3 methods:

1- Select the device with the left mouse bottom and click the hotkey “q”.

2- While the cursor is over the device, click the hotkey “q”.

3- Select the device with the left mouse bottom then press “Edit Object Properties” icon in the left icon palette

This will open the edit object properties window. Select any device properties ,now you can change the parameters you want. By using this feature, you guarantee to use the allowed Parameters’ values and update the device with the new values.

Selecting and manipulating instances

Devices can be selected with the left mouse button or by pressing the F1 function key while the cursor is over the device. With the icons in the left icon palette ,you can Move, Copy, Delete or Undo the instance.

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The Flip Horizontal and Rotate strokes allow you to quickly manipulate

selected devices as do the f and r hotkeys. Unselect a device with the Unselect All stroke or by pressing the F2 key

Generating a Symbol Step 1 Select Tools > Generate Symbol from the pull down menu.

Step 2 When you select generate symbol the next form to will popup. You can OK the

form or you can change the shape to be a buffer and add a circle to create a classic inverter shape.

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Step 3 You can select Circle from the Add Circle icon to add a circle to the inverter symbol.

Step 4 When you finish editing the symbol click Check and Save.

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Creating a Testbench

Step 1 Go back to ICstudio. Notice that now the created lib contains a cell named inverter with two views, a Schematic and Symbol view. Create a new cell with a Schematic view named test_bench.

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Step 2 Now instantiate the new inverter symbol by selecting Add > Instance from the left icon Palette or pressing the hot key i. Select the Symbol view of the inverter cell.

Step 3 Add the IN and OUT net as before by selecting the hot key i. Name the nets with hot key “q”.

Step 4 Add VDD and Ground ports in a similar fashion.

Step 5 Add a DC voltage source dc_v_source, from the MGC_IC_SOURCES_LIB. Change the value of the DC property to be 3.3V. Add PULSE voltage source pulse_v_source and change the value of the pulse_value property to be 3.3V change also the delay to be 0S.

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The test_bench schematic should look similar to the next figure.

Step 6 Select Check and Save to Save schematic changes.

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Simulating Schematic Simulating the Testbench

Step 1 When you have no errors select the Simulation icon from the left icon palette to go into design context and simulate our design.

Step 2 Click ok when this form appears. Now you are in the Design context and need to setup the analysis type, plots and load in the Eldo models

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Step 3 Load the Eldo models, To load the library,Select Setup > Models Libraries, Browse for the Library path and its Name.

Step 4 To load the Eldo models in one include file, Select Setup > Include Files, Browse for the include_all file

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Step 4 Select the Setup Analysis icon. This will open a form for you to select the analysis type. Select Transient followed by selecting the Setup button.

Step 5 Let the Stop Time (TSTOP) be 100n and OK the two forms.

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Step 6 Now select the IN and OUT terminals , Click left mouse at the net IN and use shift to continue select the OUT net.

Step 7 While the IN and OUT nets are selected press on the Setup Outputs > Edit icon from the Icon Palette. This dialog box will appear. Select Selected Components tab make sure the Plot Items(s) is selected, and click OK.

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Step 8 Another window will appear asking about the plot type, select Individually then OK.

Step 9 Create a netlist by selecting Simulation > Create Netlist . This will open a xterm window. Press Return to close the xterm window.

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Step 10 View the netlist by selecting: View > Netlist File.

Step 11 The netlist should look similar to this:

Step 12 Close the netlist window (Shift–F12) or right-to-left stroke and select Run icon. This will open another xterm.Press Return to close the Simulation xterm.

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Step 13 View the simulation results by selecting the View Outputs icon. This will open EZWave for you with the output waveforms. This is how the waveforms look like after zooming.

Step 14 Close EZwave and DA_IC.

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Creating a Layout Cell View Step 1 To create a layout cell view select the inverter cell and click on File > New >

View from the menu bar. A window will pop-up asking for the cell view type. Choose Layout as view type, the view name will be named automatically Layout.

Step 2 By pressing Next a new window will appear asking you for the Connectivity Source select Schematic to open IC -Station in the SDL mode.

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Step 3 By Pressing Finish this will open IC-Station.

Creating SDL

Step 1 Make the Schematic window active by selecting it with the LMB. Press on the Auto Pick & Place icon from the Icon Bar. The tool will place the devices one by one.

IC Window

Layer Palette Pull Down

Menu

Schematic Window

Icon Bar

Icon Palette

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You have now instantiated the pmos and nmos and the connectivity is maintained as illustrated by the fly lines. Next you will add ports and complete the routing.

Step 2 With the layout window active, select the Pick Place Ports icon from the icon bar.

Step 3 Select the VDD port and select MET1 as a layer for this port. The Width and Height will be updated automatically according to the minimum metal1 dimensions. Press Apply to place the port.

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Step 4 Place the rest of the ports.

Step 5 To add the substrate contacts to the mosfets. Select Add Device icon from the Left Hand Palette then select Path-based Guard Band select psub.

Step 6 Do the same for but choose nwell instead of psub.

Step 7 To add the over flow lines for both psub & nwell , Select psub then Connectivity > Net > Add to Net to set psub to Ground and the same for nwell to set it to VDD.

VDD

IN OUT

GROUND

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Routing Layout Step 1 Select the Layout window and maximize it. This will create a full window image of

the layout.

Step 2 To start routing press on the IRoute icon in the icon bar. Once you place the cursor on where you want to start routing, it will start guided by the fly lines. You can toggle between the connectivity layers by pressing space-bar.

After completion,You should see something similar to the shown below

VDD

IN OUT

GROUND

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Step 3 Add text labels to the ports to make them recognizable by LVS by pressing the hot key l or select Add > Text

This is how the layout will look like

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Verification of Layout Now you can verify the layout by running DRC and LVS checks. we will run Calibre Interactive.

Running Calibre Interactive DRC Step 1 Select Tools > Calibre > Run DRC entry from the pull down menu.

Step 2 This will bring up the Calibre Interactive – DRC.

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Select Rules button and notice that the rule file is loaded automatically.

Step 3 Select Run DRC.

Step 4 The Calibre RVE window will popup and you should see the following results.

Running Calibre Interactive LVS

Step 1 Select Tools > Calibre > Run LVS entry from the pull down menu.

Step 2 The Calibre Interactive – LVS window will popup. Make sure Export from schematic viewer is selected while the Inputs and Netlist tabs are active as shown.

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Step 3 Select Run LVS.

Step 4 Calibre RVE window will popup and you should see results similar to this.

Running Calibre Interactive PEX Step 1 Select Tools Calibre > Run PEX entery from the pull down menu. Step 2 The Calibre Interactive – PEX window will popup.

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Step 3 Choose the output netlist to be in DSPF Format as in the figure below Step 4 Select RUN PEX. Step 5 The RVE window will popup and should look as follow.

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Step 6 The pex netlist will appear and should look as follow. Step 7 Open the test bench schematic and enter the simulation mode, then select the inverter block. Step 8 Select Tools > Parasitics > Add DPSF.

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Step 9 This window will pop up. Select the extracted PEX netlist.

Step 10 Run simulation. Step 11 View the wave’s output signal.

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Step 12 There is a noticable increase in the delay due to the parasitics.

This completes the Design Kit User Guide.

Thank you